But that is not necessary the ideal method. Because then you need to compute whether the premutations are even or odd--> That is time consuming.

Now if I recall I never said it was the ideal method of computing it.

Similarly if the discussion was about the quadratic formula, and what
happens for cubics and quartics, just because I might mention the
existence of the corresponding formulae does not mean that I recommend
their use for anything other that as a decorative element for a wall
paper design

RonL

(Oh and it/they may have some use as the machinery in the proof
of other results)

I'm amazed I still remember anything about permutations. So much of the stuff I did at uni has been lost to the void. The formula looks familiar enough for me to think I've seen it before. It would have taken ages to find it though and I hadn't even thought to look. Thanks for satisfying my curiousity.